Collapsible carton



F. A. RYDER COLLAPSIBLE CARTON June 27, 1961 3 Sheets-Sheet 1 Filed April 17, 1957 INVENTOR. ar/98 c2. La /99 BY XMWMMQG-M we June 27, 1961 F. A. RYDER COLLAPSIBLE CARTON 3 Sheets-Sheet 2 Filed April 17, 1957 INVENTOR.

June 27, 1961 F. A. RYDER 2,990,099

COLLAPSIBLE CARTON Filed April 17, 1957 5 Sheets-Sheet 3 United States This invention relates to an improvement in a carton, that is to say a paper board car-ton and it is concerned especially with a bottom construction of the kind generally referred to in the trade as an automatic locking bottom. Cartons having automatic locking bottoms are designed to be completely fabricated by the box maker, usually by means of automatic equipment, and the construction is such that the completed box or carton is delivered to the customer in a collapsed condition.

This type of carton embodies a rectangular tubular body which is collapsed to a flat condition by being folded at diagonally opposed corners of the body, and the bottom forming elements are disposed within the collapsed body and automatically adjust themselves to bottom forming position when the body is distended to open position.

The main objects of the present invention are to provide an automatic locking bottom for cartons in which the bottom forming elements are very freely adjustable from collapsed condition within the collapsed tubular body to bottom forming condition as an incident to distention of the body; to provide a bottom construction of the character indicated which will be securely locked in bottom forming position and which will provide strong support for whatever material is packaged in the container; to provide a carton of the character indicated in which bottom parts which are glued together may be more securely glued together than has heretofore been practicable; and to provide an automatic bottom carton formed from a blank which may be glued and folded on a straight line machine, as distinguished from a special spot-gluing machine which has usually been required for fabricating cartons of the automatic bottom type.

Other objects and advantages of the invention will be understood by reference to the following specification and accompanying drawings wherein there is illustrated the bottom portion of a carton embodying a selected form of the invention.

in the drawings:

FIG. 1 is a plan view of the blank from which the carton is constructed;

FIGS. 2 and 3 represent successive steps in the folding of the blank and gluing thereof to form the carton;

FIG. 4 is a plan looking into the carton in partially distended condition;

FIG. 5 is an outside bottom plan of the carton in the same position as represented in FIG. 4;

FIG. 6 is an outside bottom plan illustrating another position of the parts when the carton body is distended to a greater extent than shown in FIGS. 4 and 5 and is approaching full distended position;

FIG. 7 is an outside bottom plan of the carton in fully distended position; and

FIGS. 8, 9 and are cross sectional views respectively on the lines 3-3 of FIG. 6, 99 of FIG. 7, and 1919 of FIG. 7.

The carton represented in the drawings is formed from a blank which, as shown in FIG. 1 comprises front and back panels 1 and 2, narrower side wall panels 3 and 4, a glue flap 5, and bottom flaps foldably connected to the bottom edges of the walls 3, 1, 4 and 2 respectively by folding creases 6, 7, 8 and 9 respectively.

The bottom flap 10 which depends from the front wall 1 is of such size that it is substantially coextensive with the bottom Wall and will cover substantially the entire atent Patented June 27, 1961 bottom area of the carton. This flap 10 ultimately becomes the innermost bottom flap in the set up carton.

The bottom flap 11 which depends from the rear wall 2 is substantially of the same width as the rear wall 2 but it is of less length than the flap 10, and is provided with a stop formed end edge for a purpose which will presently appear.

The flap 12 which depends from the side wall 3 is provided with a suitable diagonal fold line or crease 13, this diagonal fold line being disposed at approximately 45 from the fold line 6 and approximately bisecting the angle of the flap 12 between said fold line 6 and the side edge 1 of the flap. At the opposite edge of the flap 12 it is provided with a curved or arcuate edge portion 15 which extends from one end of the fold line to a point marked 16 which will ultimately be located approximately at the center of the bottom of the carton when it is distended for filling. The flap 12 also has a free end or tab portion 17 which extends beyond the terminus 16 of the curved edge portion 15. The side edge 18 of said tab portion is of angular or curved form so that the outer end portion of said tab 17 extends sidewise at least slightly beyond the point 16 as shown.

The flap 19 which extends from the bottom edge of the side wall 4 is provided with a diagonal fold line 29 which approximately bisects the angle of the flap formed between the fold line 8 and the side edge 21 of the flap. Said diagonal fold line 2a is disposed at approximately 4-5 to the fold line 8. The side edge of the fiap 18 opposite the edge 21 embodies a curved or arcuate edge portion 22 which terminates at a point marked 23 which, like the point 16 in the flap 12, will ultimately be located approximately at the center of the bottom of the carton when it is distended for filling. This flap 19 also has a free end or tab portion 24 which extends beyond the terminus 23 of said arcuate edge 22. The tab portion side edge which extends from said terminus 23 is formed to provide a short lateral ear or tongue 25 which extends sidewise beyond said terminal point 23 and so as to provide, in effect, a recessed edge portion 26.

The angle between the fold lines 13 and 20 of the flaps 12 and 19 respectively and the edges 14 and 21 respectively of said flaps may be slightly less than 45 as a result of slight angularity of such edges 14 and 41 for purposes of clearance between said edges and the inside Walls of the carton during setting up of the collapsed carton. Hence, said fold lines 13 and 20 may not exactly bisect the angles mentioned. For similar clearance purposes other edges of the various bottom flaps may be cut back or disposed at angles as shown.

To form the blank of FIG. 1 into a carton, the flaps 12, 10, 19 and 11 are folded upwardly over the inside faces of the body walls 3, 1, 4 and 2 respectively. The flaps 12 and 19 are also refolded on their diagonal fold lines 13 and 29 respectively by turning the free end portions of said flaps downwardly into overlying relation to the upturned or inner more or less triangular portions 29 and 30 which are defined, as to the portion 29, by the fold lines 6 and 13 and the arcuate edge 15, and as to the portion 39, by the fold lines 8 and 20 and the arcuate edge 22. Adhesive is then applied as indicated at 31 and 32 to the exposed faces of the end portions of the down turned free end segments 33 and 34 respectively of said flaps 12 and 19 and adhesive is applied as indicated at 35 to an inner portion of the glue flap 5 leaving an outer adhesive free portion 5a. The adhesive areas 31 and 32 will ultimately engage areas indicated at 36 and 37 respectively on the flaps 10 and 11, and, if preferred, the adhesive may initially be applied to said flaps 10 and 11 instead of to the end portions of the flap segments 33 and 34, or in some instances, and dependingupon the kind of 3 adhesive used, adhesive may be applied to all of said areas 31, 62, 35, 36 and 37.

The blank prepared as shown in FIGURE 2 and preferably having adhesive applied to only said areas 31, 32 and 35, is next folded along the fold line 27 between walls 3 and 1 and along the fold line 28 between the flaps 2 and 4, the folding being done so that the glue flap will overlap the free side margin of the wall 3 and become adhesively secured thereto. The adhesive free portion 5a of the glue flap '5 provides an area which may be grasped if one desires to tear the adhesively engaged flap 5 from the Wall 3 and thereby open the carton. Incident to such folding of the walls, they are formed into a collapsed tubular body, and adhesive connection is established between the folded bottom flap 12 and innermost bottom flap 10, and between the folded bottom flap 19 and the bottom flap 11.

Because of the diagonal folds in the bottom flaps 12 and 19, and the adhesive connection of their outer or free end portions to the bottom flaps and 11, distention of the collapsed tubular body will cause said flaps to automatically fold from the upwardly and inwardly turned collapsed position to horizontal bottom forming position.

The relationship of the parts when the carton is partially distended is shown in the inside and outside plan views, FIGURES 4 and 5. As the tubular body of the carton is adjusted or distended to more nearly its final rectangular position, the folded bottom flaps 12 and 19 respectively are, of course, necessarily unfolded towards flat position so that the segments 33 and 34 thereof, which are adhesively secured respectively to the bottom flaps 10 and 11 will pull said bottom flaps 10 and 11 downwardly toward bottom position.

As shown in FIGS. 6 and 8, during the operation of distending the carton, the rounded or arcuate edges and 22 of the diagonally folded flaps 12 and 19 ride on the outer faces of the flaps 11 and 10 respectively. The movement of the arcuate edges over the faces of the flaps 11 and 10 is not a rolling movement but instead is a sliding movement in both lateral and edgewise directions in firm frictional engagement with the respective flaps 11 and 10; said frictional engagement, in a carton of the proportions illustrated, begins to take effect when the carton is distended to a position intermediate the positions shown in FIGS. 5 and 6, i.e., when the angle of the side wall 3 relative to the wall 1 is in the neighborhood of 70. Said frictional engagement gradually increases during the distending operation until the carton is in its fully distended condition and the bottom construction fully adjusted to flat bottom position. When flat bottom position is reached, the inside faces of said flaps 12 and 19 bear flatwise on the underlying flaps 11 and 10 respectively, the flap 12 also bearing flatwise on the underlying portion 24 of the flap 19 which similarly, also bears flatwise on the underlying portion 17 of said flap 12. This flat facewise inter-engagement is quite strong and resists collapsing of the carton even though there is a significant degree of resiliency in the fold line portions of both the bottom structure and the body of the carton which tends to return the carton from distended condition to collapsed condition. Any substantial movement of the flaps of the bottom structure toward collapsed condition will restore the said frictional engagement of the arcuate edges 15 and 22 with the underlying flap portions. This frictional edge engagement is very strong and its restoration requires considerably more force than remains in the various bottom and body fold lines so that the carton is very efiectively held in distended condition as an incident to said friction forces. As seen in FIGURE 7, the diagonally foldable bottom flaps 12 and 19 have convex arcuate edges 15 and 22 respectively which form, in eifect, an ogee curve which interconnects diagonally opposed corners of the bottom of the distended carton.

, It will be observed that there is no positive lock to hold 4 the carton distended since the point 23 and edge portion 26 of the flap 19 are not restricted against movement away from the point 16 of the flap 12 (see FIG. 7) except by the frictional engagement of the flaps 12 and 19 with the respectively underlying portions of the other flaps.

The curvature of the arcuate edges 15 and 22 is perhaps not to be characterized as critical since some variation thereof is permissible even in the carton proportions shown. For other carton proportions some variation may be required to obtain the most desirable results. Variation of the curvature affords a means for controlling the friction which said edges produce to control the distention of the carton after it is distended. Said arcuate edges preferably extend in a continuous, smooth are from the respective terminal points 16 and 23 to points adjacent the diagonally opposite corners of the carton.

To locate the position of the arcuate edges 15 and 22, the points 16 and 23 are first determined. The dimensions A and B respectively between the point 16 and the flap edge 14 and between the point 23 and the flap edge 21 are approximately /2 or just a trifle less than /2 of the width C of the narrow side walls 3 and 4 from which said flaps 12 and 19 depend. These walls 3 and 4 are of like width so that the dimensions A and B are also alike. The dimensions D and E respectively between the point 16 and the center of the fold line 6 for the flap 12 and between the point 23 and the center of the fold line 8 for the flap 19 are approximately /2 or a trifle less than /2 of the width F of the Wall panels 1 and 2. The measurements C and F refer to the distances measured from the centers of the various fold lines.

The curvature of the are 15 is generated by a radius which is only slightly less than the dimension C, usually about A; inch less when the dimension C is about 3 /2 inches and the dimension F is about 4% inches. The center about which such radius is swung is so positioned that the arc will join the point 16 with the free edge 38 of the panel 3 as shown.

The radius for the arcuate edge 22 is also selected to be slightly less than the dimension C, preferably about as above set forth and the center about which the radius is swung to generate the curved edge 22 is located so that the curved edge 22 will join the point 23 wit-h a point in the fold line 8 spaced from the fold line 39 between the wall panels 1 and 4. This point in the fold line 8 may be about A; of an inch from the fold line 39.

The relationships indicated provide very satisfactory results but some variation is possible. The thickness of the board stock used for forming the carton may have a bearing on the curvature selected for the said arcuate edges 15 and 22. The friction may be increased by modifying the curvature so that there is a greater bulge as indicated by the dotted line 22a in FIG. 1 especially at the end of the curved edge adjacent the fold line 8 which is the portion which engages the underlying flap portions immediately before the fully distended position is reached. Reduction of the friction may be effected by flattening the curve. It has been found that the use of arcuate edges generated as above described in a carton having the wall widths mentioned, provides arcuate edges of which the portions which engage underlying wall portions gradually increase in length and in frictional contact with the underlying flap portions as the bottom structure approaches its flat, fully distended position. Accordingly, collapsing of the carton from fully distended'condition is effectively resisted by the relatively great resistance to restoration of engagement between the arcuate edges 15 and '22 and the respective underlying flaps.

As shown in FIG. 6 the arrangement is such that as the carton nears its fully distended position, the ear or tongue portion 25 of the flap 19 moves into underlying relation to the flap 12 and the end portion 17 of the flap 12 moves under the flap 19. In the fully opened position of the carton, the flap 12 bears frictionally on the underlying portion 24 of'the flap 19 and on the underlying flap 11, and flap 19 bears frictionally on the underlying portion 17 of the flap 12 and on the underlying flap 10. The movement of the arcuate edges 15 and 22 over the surfaces of the flaps 11 and as shown in FIG. 6 into overlying relation to the flap portions 24 and 17 respectively is smoothly accomplished because of the curvature of said edges 12 and 22. As shown in FIG. 6, when the arcuate edge first begins to overlie the ear portion of the flap 19 the edge portion 15 which overlies said ear portion 25 is spaced upwardly therefrom incident to bearing of a portion 15a of the edge '15 on the underlying flap 11. Similarly, when the edge 22 of the flap 19 first moves to an overlying position to the portion 17 of the flap 12, a portion 22a of the edge 22 is in engagement with the flap 10 and holds an adjacent portion of said edge 22 in upwardly spaced relation to the underlying flap portion. Hence, there is no significant likelihood that folding of the bottom structure to flat bottom position will be obstructed or hampered by abutting engagement between any portion of the edges 15 and 22 with the opposite edge portions of the flaps 19 and '12 respectively. The carton may, therefore, be set up at a very high rate of speed with practically no danger of jamming incident to improper edge engagement between the relatively moving flap portions.

As shown in FIGURE 7, the described construction provides a bottom which presents simple, neat appearing lines on the bottom of the carton and the outermost flaps 12 and 19 are held in snug face-to-face relationship with the respective immediately overlying flaps. The end portions 17 and 24 of said outermost bottom flaps are held snugly to the immediately adjacent bottom flaps 10 and 11 by the adhesive connections 31 and 32 so that there is a minimum of danger that such corner portions will separate from the overlying flap portions and project in an objectionable manner. Hence, the bottom construction on the outside of the carton is maintained in a desirably smooth and flat condition when the carton is fully set up. The full area innermost bottom fiap 10 provides a smooth inner bottom and helps substantially to prevent leakage of powdered, granular or other fluent materials through the carton bottom.

Although collapsing of the carton after it is once set up is not generally important in cartons of this type, recollapsing of the carton may easily be effected by exerting slight upward pressure on the central portion of the bottom structure. Such upward pressure tends to refold the foldable bottom flaps 12 and 19 which, in turn, tend to cause the carton walls to fold on themselves toward the initial collapsed condition.

A carton having walls of the width above set forth and a top-to-bottom dimension of about 6% inches may be typified by cartons designed for containing /2 gallon of material, for example ice cream. The automatic bottom structure may also be embodied in car-tons of other sizes, for example one designed for containing one gallon of material in which one pair of walls would be approximately 4 /2 inches wide and the other pair 5 inches wide with a top-to-bottom dimension of about 6% inches. In such a carton the lengths of the curved edge corresponding to the edges 15 and 22 would be somewhat longer and in order to provide the desired degree of friction, they should be properly curved. An empirical rule for determining the radius of the curvature is that the radius should be of a length approximately equal to the length of the cord of the arcuate edges. The length of this radius is variable and an empirical formula for its variation is that it should be within the range of 75 to 125 percent of the length of said cord. In general, the friction between the curved edges and the flaps engaged thereby is decreased as the radius of the curve is lengthened and the curve flattened and said friction is increased as the radius is shortened (within said range) and the curvature of the arcuate edge increased.

When the carton is distended, positioning of the innermost flap 10 inside of or over the second flap is a function only of the greater length of said flap 10 as compared wi-th the length of the flap 11. This is quite clearly indicated by reference to FIGURE 8.

The flap 11 has one end portion 11a of a length which substantially corresponds to the Width of the glue receiving end portion 24 (including the lip or ear 25) so that the entire length of the glue strip 32 will be adhered to the widened end portion 11a of said flap 11 as indicated at 37 in FIG. 2. The remainder of the ilap 11, that is to say the portion 11b, is made shorter so that the free edge 11c thereof will register with or be located just short of the recessed edge 26 of the outer segment or portion 24 of the flap 19 when the glue strip 32 is adhered to the flap 11. The angular cut 11d on the end of the flap 11 is so located that it will register with or be located in slightly spaced relation to the angular edge 25a of the ear 25 as best shown in FIGS. 6 and 7. If preferred, the flap 11 may be made of uniform length corresponding to the length of the portion 11b in which case the glue strip 32 should be correspondingly shortened so that said strip will become attached only to the flap 11 without also contacting any portion of the wall 2.

In the arrangement illustrated, glue is applied continuously across the entire widths of the free end portions of said flaps 12 as shown at 31 and 32. This is advantageous in that it facilitates production of the cartons by a socalled straight line gluing operation as distinguished from a spot gluing operation. In cartons of this general character as heretofore made, spot gluing has been employed for applying glue to a pre-folded flap portion in order that the glue be confined within a limited area. Spot gluing involves difficulties of maintaining proper registration of the flaps of the cartons with the glue applying pads of the gluing mechanism. In the described construction a continuous line or area of glue extending from one edge to the other of the end portions of the flaps 12 and 19 avoids any registration diiiiculties and permits the use of a simple continuous line glue applying wheel without special pads or special areas for applying the glue.

In the construction shown, the diagonally foldable flaps 12 and 19 have corners rounded off as indicated at 40 and 41 partly as a matter of appearance in the set up carton as represented in FIG. 7 and partly to eliminate the need for an excessively large area of glue attachment of the end portions of the flaps 12 and 19 to the flaps 10 and 11 respectively to avoid the leaving of unattached corner portions.

The innermost bottom flap 10 has one edge 42 recessed relative to the line of the fold 27 so as to reduce to a satisfactory degree the friction which occurs between said recessed edge 42 and the wall 3 of the carton during the distention or setting up of the carton. Similarly, both side edges of the flap 11 are angled toward each other from the hinge line 9 so as to permit free folding movement of said flap 11 without interference from the side walls 3 and 4.

The described bottom construction may be employed in cartons of various kinds and for a wide range of pur poses. In the present disclosure no top closure has been shown but any suitable or known end closure may be provided; for example, an end closure formed of flaps integrally and foldably connected to the upper ends of some or all of the walls of the body, or a shallow cap like cover may be provided.

Various modifications may be made in the described bottom structure while retaining the principles of the invention.

I claim:

1. A collapsible carton having an automatic locking bottom, said carton being formed from a unitary blank and comprising four foldably interconnected side walls which are disposable between a flat collapsed condition and an erected tubular formation having a rectangular cross section, and a bottom wall formed of bottom flaps which are disposable incident to erection of the carton from positions between the collapsed sidewalls to bottom-wall-forming positions generally perpendicular to the erected side walls, said bottom wall comprising an innermost bottom flap foldably connected to the bottom edge of one of said side walls, said innermost flap being generally coextensive with said bottom wall, a second bottom flap foldably connected to the bottom edge of the opposite side wall and adapted to immediately under lie the inner most flap when the car-ton is erected, and a pair of diagonally foldable flaps which are respectively foldably connected to the bottom edges of the other pair of side walls and which overlie said innermost and second bottom flaps when the canton is erected, said pair of diagonally foldable flaps having outer end portions defined by diagonal fold lines which extend across said flaps from diagonally opposite corners of the carton, said end portions having outermost margins which are disposed, when the carton is erected, with their edges in generally parallel relation to the foldable connections between said diagonally foldable flaps and the side walls, which are arranged in said blank to permit straight line application of glue along the entire length of their edges, and which are respectively fixedly attached along the entire length of their edges to said innermost and second bottom flaps, said end portions having edge segments which are spaced inwardly of said outermost margins and are adapted to meet each other approximately at the center of said bot-tom wall when the carton is erected, said diagonally foldable flaps having convex arcuate edges which extend from said edge segments to the respectively adjacent other corners of the carton, said arcuate edges being formed to frictionally bear on the respectively underlying flaps incident to initial relative movement of the bottom wall flaps during erection of the carton to permit partial entry of said end portion of each of said diagonally foldable flaps .under the other of said diagonally foldable flaps without interfering abutting engagement of said arcuate edges and the edges of said outermost margins of said end portions, said arcuate edges being formed to elfect gradually increasing frictional engagement with the underlying flaps incident to complete erection of the carton to thereby maintain the carton is erected condition, said edge segment of said end portion connected to said second bottom flap constituting a notch having an edge disposed generally parallel to the side wall from which said second bottom flap extends so as to permit initial collapsing movement of said bottom flaps incident to the application of pressure direct centrally against said bottom wall.

2. A collapsible carton having an automatic locking bottom, said carton being formed from a unitary blank and comprising four foldably interconnected side walls which are disposable between a flat collapsed condition and an erected tubular formation having a rectangular cross section, and a bottom wall formed of bottom flaps which are disposable incident to erection of the carton from positions between the collapsed side walls to bottom-wall-forming positions generally perpendicular to the erected side walls, said bottom wall comprising an innermost bottom flap foldably connected to the bottom edge of one of said side walls, said innermost flap being generally coextensive with said bottom wall, a second bottom flap foldably connected to the bottom edge of :28 the opposite side wall and adapted to immediately underlie the innermost flap when the carton is erected, and a pair of diagonally foldable flaps which are respectively foldably connected to the bottom edges of the other pair of side walls and which overlie said innermost and second bottom flaps when the carton is erected, said pair of diagonally foldable fiaps having outer end portions defined by diagonal fold lines which extend across said flaps from diagonally opposite corners of the carton, said end pontions having outermost margins which are disposed, when the carton is erected, with their edges in generally parallel relation to the foldable connections between said diagonally foldable flaps and the side walls, which are arranged in said blank to permit straight line application of glue along the entire length of'their edges, and which are respectively fixedly attached along the entire length of their edges to said innermost and second bottom flaps, said end portions having edge segments which are spaced inwardly of said outermost margins and are adapted to meet each other approximately at the center of said bottom wall when the carton is erected, said end portions extending when the carton is erected on both sides of said edge segment toward the side wall opposite that from which the attached bottom flap is foldably connected, said diagonally foldable flaps having convex arcuate edges which extend from said edge segments to the respectively adjacent other corners of the carton, said arcuate edges beingformed to frictionally bear on the respective underlying flaps incident to initial relative movement of the bottom wall flaps during erec tion of the carton to permit partial entry of said end portion of each of said diagonally foldable flaps under the other of said diagonally foldable flaps without interfering abutting engagement of said arcuate edges and the edges of said outermost margins of said end portions, said arcuate edges being formed to effect gradually increasing frictional engagement with the underlying flaps incident to complete erection of the carton to thereby maintain the carton in erected condition, said second bottom flap having an edge pontion which registers with said edge segment and the adjacent outermost side edge of the attached diagonally toldable flap and which extends with the end portion of said last mentioned flap between said innermost flap and the other of said diagonally foldable flaps in closely adjacent relation tov the fixed connection therebetween so as to increase the frictional engage ment which maintains the canton in erected condition, said edge segment of said end pontion connected to said second bottom flapconstituting a notch having an edge disposed generally parallel .to the side wall from which said second bottom flap extends so as to permit initial collapsing movement of said bottom flaps incident to the application of pressure directed centrally against said bottom wall.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2390 099 June 27 1961 Fred An Ryder It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 7 line 10,, for "inner most" read innermost '];l1:16 44 for '15-" read 1n same column, line 50 for dlrect" read dlrected Signed and. sealed this 26th .day of December 1961.,

(SEAL) Attest:

ERNEST W. SWIDER v DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DC 

